1. Field of the Invention
The present invention relates to warp knitting fabrics for zippers, and more particularly to such a warp knit fabric which has reinforced zones for supporting the synthetic coil (teeth) against transverse stretching forces.
2. Description of Related Art
Referring to FIG. 4, a regular clear zipper 10 is generally comprised of two fabric tapes 12, two interlocking coils 14 respectively fastened to the fabric tapes 12, and a slide 16 to close/open the interlocking coils 14. When the coils 14 are fastened to the respective fabric tapes 12 by stitches, the fabric tapes 12 are folded up and sealed by a hot press, and then the slide is coupled between the coils 14. When pulling the slide 16 to close the interlocking coils 14, folded edges 13 of the fabric tapes 12 are abutted against each other, enabling the interlocked coils 14 to be received on the inside and kept out of view. Because clear zippers are commonly used with summer clothes and the fabric tapes 12 of the invisible zippers each have a folded edge 13, the fabric tapes 12 must be made light and highly flexible. Therefore, fabric tapes for invisible zippers are generally made by warp knitting. As illustrated in FIG. 5, the fabric tape 12 is comprised of a plurality of first knitting yarn 121, a plurality of second knitting yarns 122, and a plurality of third knitting yarns 123. The first knitting yarns 121 advanced knitted into laps. The second knitting yarns 122 are knitted into a tricot. The third knitting yarns 123 are alternatively and knitted between its left side and right side. Further, the coils 14 are respectively made from a synthetic wire directly fastened to mounting areas 124 at the respective fabric tapes 12. The mounting areas 124 are spaced from the two side edges of the respective fabric tape 12 at about two stitches. Because the mounting areas 124 are close to the side edges of the respective fabric tape 12, they tear easily when the zipper 10 is stretched transversely. When the zipper 10 has a tear in the mounting areas 124, the fabric tapes 12 become unable to support the coils 14 in position, and the coils 14 may be deformed, thereby preventing the coils 14 from becoming locked/unlocked. In order to reinforcing the structural strength of the fabric tapes 12, fill knitting yarns may be knitted with warp knitting yarns. However, such a knitting method greatly increases the thickness of the fabric tapes. Fabric tapes made according to such a knitting method are suitable for use with winter clothes.